Electric discharge tube



'Dec. 17, 1940. J. L. H. JONKER ETAL 2 ELECTRIC DISCHARGE TUBE Filed Oct. 5, 1958 bbbb II INVENTOR. JOHAN L. H. JONKER ERARD C.A.M. MOUBLS,

ATTORNiY.

PatentedDec. 17; 1940 an-electric discharge t'ube for indicatin'g'voltages' hereinafter termed tuning indicator,

' 1 Such tuningindicators for. use in wireless re-f ceiving 'setsl'aneasuring apparatus or-thelikearef known in 'various forms one ofthe kind most in use at the present day being-that in which the I electron current"emergingfrom'a cathode is controlled by an electrode having a positive poten tial-F and being preferably shaped in tthie form of a rodithe electron-current striking a" fluorescent anode; This electrode systemmay'be assembled in ,a"-single tubea second electrodefsystem 2, surrounding -the s'amecathode, the control ere t'rode 0f the =first-mentioned system being com -nected 'to' "the 'anodexof the last-mentioned one. j

f I offal-given shape which is substantiallyidentical with that of tlfieapertureinthediaphragm;

. 1 Iii fcontradistinction to' the well -know'n 'indi 'cato'rs"a tuningindicator"of the said kind is very similar.'toicathodeeray tubes, but-the great di fgrenamer1-om=tnewe1 -known cathode-ray tubes is" that" the screen has projected on it a divergirig phlegm; Thewell-known-tubes, such'asBraun tubes or the like, are so constructed that-either a converging beam or a parallelbeam from which 40 a portionis cut outby an aperture formed in one ofthe damages is thrown on 'to .the'screengi 'In'a tube in adevic e' according to the invefi 3 tion the focal distance of the electron-diverging I lens may be altered by modifying the potential of at least one of the "electrodes that constitute the lens. Thus the distance of the focusof the lens' from ,the diaphragm is also altered and the 1 partwhich is cut out from the beam by the dia-' 'phragmwill be possessed of a different diverg- 0 ence and consequently form: on the fluorescent "screena larger or smaller image. It has been "found that in spite of the. focal distance being altered the image on the screen conserves its definition. I Y- {$5 In one form of'construction of the present in- I I T I qr s Htee TUB Johan Lodewijk Hendrik" Junker and Gerard ,i'ehalrlesa Antoine Marie-:.,Moubis, .Eindhoven;

Netherlandalassignors, byimesnje assignments, toRadioCorporation of America -New York, r q

In the Netherlands October '13; 1337-" v I, t m -theme; This invention 'relates-to a device 'comprising "g-The present invention'relates to a "devic'efcomeprisin -a= t1iningindicator of a constructibn 3 Whichis widelyfdifi'erent from that hereinbeforef nientionedi according; to "the invention 'th-e ele'c- 1 trons emanating'-'from*the cathode of'the tun ,1 v ing indicator are accelerated by-*anaccelerating anode and then'unitedbyan' 'electroriiclens t'o f01'11*l a diverging beam} A portion-oi this beam is 25 thn scut outby adiaphr'agm at somedis'tanc'ein front" 'ofthe fluorescent screen a'ndf'th bea'rjn l which passesthrough the apertureofthe di'a phra'gm" forms on the fluorescent screen an image v v aceompanying drawing; in w l .ami r e m lwa a l t Application 0ctober'5, 1938; Serial Nil-233,362

'v tigngthe 'V'olta'ge 'to be indicated'by the :ind1'-:-

cator i's placed With advantage on one ofthe electrodes or the lens, the best result being obtain'edif a negative bias-is applied to this elec n trode-and'if use ismade of such'a device that the .5 voltage to be indicatedreduces the negative'bias of the said electrode and thus increases theidivergence 'of the part of the beam which 'is cut clitby the aperture in the diaphragm iand the imageof this apertureon'the fluorescent"screen. 10

By placinga negativebiason the electrode to which the voltage isapplied it is ensured that when 'nrestthe beam yields buta very" small sp'o the'fluorescent screen. 1

derstood and readily carried into efiect it: will now be described' more fully with reference to the v ichla device accordingfltotfiepres'ent invention is shown; l Referr n oft effi r 'q r he d w f es'ignate's atuning indicator having a cathode 2",j"ar' 1 'accelerating anodet, two electrodes 4 and. SIin'eachof which an aperture is formed, a diaphragm ;'in"which theaperture to be repr o s, "formed; and "an 'electrode l'. Intermediate-"the electrodes '4 and San electronic lens is iormed' by} connecting one of these electrodes to o a tappingof'a'potentiometer 8 arranged between the positive term'inalpf a source of highvoltage and the earth. Said potentiometer is possessed in addition of tappings for the electrodes 2, 3, 6

, and 1. The electrode 6 has formed init a star- 45 shaped aperture and the divergent beam formed v by the electrodes 4 and 5 passes for a small part through this aperture and then falls on to a fluorescent screen 9 arranged at'the end of the tube 1 thereby forming an enlarged replica of the aper- 60 ture, on the fluorescent screen. The electrode 4 of the lens is connected to the point whose voltage is to be reproduced optically; In the circuit shown this is a point of a wireless receiving circuit in which the tube l indicates the tuning of a 88 "I'he diaphragm-may be internally connected to r set. The circuit comprises a diode which detects the high-frequency alternating voltage and thus sets up a potential difiference across the resistances I l and [2. The point A is thus given a positive voltage which is supplied to the electrode 4 through an electric filter formed by a resistance I5 and condensers l3 and M. The said electrode 4 is given a negative bias relatively to the cathode 2 since the latter is connected to a tap.-

of this electrode 4 is established so that the image on the fluorescent screen has minimum di--' mensions. If the negative voltage of the electrode 4 is decreased due to the fact that the point A is given a positive voltage, the dimensions of the fluorescent image are increased. The point A is most positive when the set is tuned completely and the correct tuning is therefore found by adjusting to the maximum size of the image on the fluorescent screen. As an alternative, the electrode 4 may be given a positive bias and in this case the negative voltage is tapped off, for example, the point B. Thus the size of the fluorescent image decreases on the set approaching its tuning. In the circuit shown the resistances H and [2 form a potentiometer the point C' of which is earthed.

, Obviously, the electrode 4 may have supplied to it anyvoltage to be measured and the invention is not limited to the use of tuning indicators in wireless receiving sets.

What We claim is:

1. An electronic tuning indicator tube having an electrode structure consisting of an electron source to generate an electron beam, an electron responsive target oppositely disposed from said electron source, a pair of electrically connected apertured electrodes with their apertures axially aligned between said electron source and said target and the electrode of said pair nearer the said target being the electrode most adjacent said target, an intermediate apertured electrode between said pair of electrodes, electrode means between said two electrodes and said electron source to control the divergence of the electron beam through the aperture of said intermediate electrode to electronically image the aperture in said intermediate electrode over continuallydiverging paths on said target.

2. An electronic tuning indicator tube comprising an evacuated envelope enclosing a source of electrons and electrode structure consisting of an oppositely disposed target adapted to become luminescent when bombarded with electrons from said source, means comprising an apertured anode to maintain the emission from said source substantially constant, three axially aligned apertured electrodes between said anode and said target, the aperture of the intermediate electrode 0 0f said three electrodes being non-circular and one of said three electrodes being wholly exposed to said target and being the nearest to said target ping of the potentiometer 8. The negative bias of any electrode in said envelope, and electrode means between said anode and said three electrodes to electronically image the noncircular aperture on saidtarget over an area on said target which is greater than the area of said noncircular aperture.

3. An electronic indicator tube having an evacuated envelope enclosing a fluorescent screen, a cathode oppositely disposed from said screen, a pair of electrically connected apertured electrodes between said cathode and said screen, one of said pair of electrodes being closer said screen than any other electrode in said tube, an electrode having a noncircular aperture, said electrode being positioned between said pair of electrodes, and

electrode means between said cathode and said pair of apertured electrodes to direct electrons from said cathode to said screen over paths diverging from a direct line between said cathode and said screen over the entire distance between said electrode having the aperture and said fluorescent screen. Y

4. An electronic tuning indicator tube having an evacuated envelope, a fluorescent screen within said envelope, and electrode structure within said envelope comprising a cathode oppositely disposed from said screen, a system of three-apertured electrodes between said cathode and said screen, the electrode of said system nearest said screen being the closest electrode to said screen of all the electrodes within said envelope to cause electrons emitted from said cathode to follow paths toward said'screen which continuously diverge over the distance separating said system of electrodes from said screen, and means including an apertured electrode between said three electrodes and said cathode to maintain the diameter of the beam impinging on the intermediate electrode of' said system of three electrodes greater than the aperture in said intermediate'electrode to image said aperture on said screen.

5. An electronic indicator tube having an envelope enclosing an electron source to emit a beam of electrons, an anode adjacent said source to accelerate the beam of electrons, a fluorescent screen oppositely disposed from said source to receive electrons from said source, a noncircular electrode having an aperture axially aligned with said cathode and anode between said anode and said screen, the noncircular electrode on each side of said electrode having an aperture, and electrode means between said electron source and the next adjacent electrode in the direction from said source to said screen to direct upon said screen a beam of electrons having a constantly increasing diameter throughout thespace from said electrode having the aperture to said screen to image an enlarged replica of said noncircular aperture on said anode.

J OHAN LODEWIJ K HENDRIK J ONKER. GERARD CHARLES ANTOINE MARIE MOUBIS. 

